Fifty years ago this month, a group of 13 men and women, seven black and six white, left Washington, D.C., on two buses bound for New Orleans.

They never made it. Ten days later, on May 14, 1961, one of the vehicles was attacked by a white mob in Anniston, Ala., the bus set on fire and the riders beaten up. The local police and state troopers made no effort to stop the violence, and the governor of the state, referring to the integrated group of passengers, sarcastically remarked that "you can't guarantee the safety of a fool."

That same day, the other bus pulled into the terminal in Birmingham, Ala., where it was met by a mob of 1,000 people who proceeded to viciously beat the riders. But as Freedom Riders, a stunning two-hour documentary being broadcast by PBS on May 16 at 9 p.m. (EST) (and reviewed by Stanley Crouch for The Root last year) demonstrates, these nonviolent activists never gave up -- and, in doing so, managed to effect real change.

"We did what all oppressed people have done throughout human history," says Hank Thomas, 70, a former Freedom Rider who was a Howard University student at the time. "You try to change things, and you pay a price for it. But you do what you have to do."

"[The riders] did not want to live, or their children to live, the way their parents had lived," adds Stanley Nelson, the documentary's writer-director. "These kids did not come out of nowhere. Every generation of African Americans had done what they could to move forward."

Trained in the nonviolent techniques of Gandhi and Martin Luther King Jr., the group was organized by the Congress of Racial Equality and included Stokely Carmichael and current U.S. Rep. John Lewis. They set out to test whether a Supreme Court decision mandating integrated facilities in interstate bus travel was actually being implemented south of the Mason-Dixon Line.

They had little trouble until they reached Alabama, which, along with Mississippi, was, says Nelson, something of a "no-fly zone" because of the level of violence directed against blacks. And in fact, some factions of the movement felt that what the riders were doing was a bit too confrontational and in-your-face, literally inviting aggressive reaction.

"Nonviolence by its very nature is confrontational," says Charles Person, 68, a former Morehouse College student who was the youngest of the first group of Freedom Riders on that trip. "You don't have a weapon, so you have to make [your opponents] feel uncomfortable."

This was brave enough. Even braver was the fact that after the buses were attacked, and the riders eventually found themselves stuck in Birmingham -- where the Greyhound company could not find a driver willing to continue the trip -- another wave of Freedom Riders, based in Nashville, Tenn., and allied with the Student Nonviolent Coordinating Committee, decided to finish what the first group had started.

What ensued from that point on was a complicated social and political dance that involved the activists, the governors of Alabama and Mississippi and the Kennedy administration, which, more concerned with international affairs, reluctantly stepped in when it realized that local authorities would do little or nothing to protect the riders from Klan-inspired mobs.

"The Kennedys were not the great civil rights heroes the way we think of them now -- at least at that time in history," says Nelson. "They were dragged kicking and screaming into [the conflict], and they changed; they became better persons because of it."

Eventually, hundreds of riders participated in the protest, more than 300 of them winding up in jail in Mississippi's notorious Parchman prison farm, where they created an informal school of nonviolent revolutionary tactics and became the shock troops of a larger movement that would change America for all time. Then, on Sept. 22, 1961, four months after the first bus left D.C., the Interstate Commerce Commission officially ended bus and rail segregation throughout the U.S.

Yet despite their bravery in standing up against the fists, chains and baseball bats of white bigots, and in effecting real progress by doing so, it's the present-day humility of the participants that really stands out. They seem to be saying that they did what they had to do, and, well, that's how it was.

"Most of us were so dedicated to the point that you wouldn't do anything to distract from the movement," says Person. "Dr. King had proven that nonviolence works, Gandhi had proved that it works. We weren't the initiators of this technique. It was just a time in our history."

"This is the story of young people at great personal risk who set out to make a change, and they did not let anything stop them," adds Nelson. "I hope after people see this film, they talk about the power we have as individuals in this country -- the power to make change."

Lewis Beale writes about film and TV for numerous publications, including the Los Angeles Times, New York Daily News and Newsday.